1. Field of the Invention
The present invention relates generally to minimally invasive and less invasive surgical access. More particularly, the present invention provides retractors for soft tissues and methods for their use to provide surgical access into body cavities.
Coronary artery disease remains the leading cause of morbidity and mortality in western societies. Coronary artery disease is manifested in a number of ways. For example, disease of the coronary arteries can lead to insufficient blood flow resulting in the discomfort and risks of angina and ischemia. In severe cases, acute blockage of coronary blood flow can result in myocardial infarction, leading to immediate death or damage to the myocardial tissue.
A number of approaches have been developed for treating coronary artery disease. In less severe cases, it is often sufficient to treat the symptoms with pharmaceuticals and lifestyle modification to lessen the underlying causes of disease. In more severe cases, the coronary blockage can often be treated endovascularly using techniques such as balloon angioplasty, atherectomy, or stents.
In cases where pharmaceutical treatment and/or endovascular approaches have failed or are likely to fail, it is often necessary to perform a coronary artery bypass graft procedure using open surgical techniques. Such techniques require that the patient""s sternum be opened and the chest be spread apart to provide access to the heart. A source of arterial blood is then connected to a coronary artery downstream from an occlusion, while the patient""s heart is maintained under cardioplegia and circulation is supported by cardiopulmonary bypass. The source of blood may be a vessel taken from elsewhere in the body such as a saphenous vein or radial artery, or an artery in the chest or abdomen such as the left or right internal mammary artery or the gastroepiploic artery. The target coronary artery can be the left anterior descending artery, right coronary artery, circumflex artery, or any other coronary artery which might be narrowed or occluded.
While very effective in many cases, the use of open surgery to perform coronary artery bypass grafting is a highly traumatic to the patient. The procedure requires immediate post-operative care in an intensive care unit, a total period of hospitalization of seven to ten days, and a recovery period that can be as long as six to eight weeks.
Recently, it has been proposed to utilize minimally invasive surgical techniques and procedures to perform coronary artery bypass grafting and other traditionally open-chest cardiac surgical procedures. A wide variety of laparoscopic, arthroscopic, endovascular, and other minimally invasive surgical therapies have been developed. These procedures generally utilize trocars, cannulas, catheters, or other tubular sheaths to provide an artificial lumen, through which specialized tools are inserted and manipulated by the surgeon.
An exemplary minimally invasive bypass method is described in U.S. Pat. No. 5,452,733, assigned to the assignee of the present application, the full disclosure of which is herein incorporated by reference. This exemplary coronary artery bypass method relies on viewing the cardiac region through a thoracoscope and endovascularly portioning the patient""s arterial system at a location within the ascending aorta. The bypass procedure is performed under cardiopulmonary bypass and cardioplegia, while the coronary anastomoses are formed within the chest cavity through the use of a plurality of trocar sheaths placed between the patient""s ribs.
Although thoracoscopic methods hold great promise for decreasing morbidity and mortality, cost, and recovery time when compared to conventional open surgical coronary bypass procedures, these methods could benefit from still further improvements. In particular, the surgical access provided by known trocar sheaths has not been optimally adapted for performing thoracoscopic coronary artery bypass. The length of conventional trocar sheaths and the small size of their lumens limits the maneuverability of surgical instruments and inhibits the ability to look directly into the chest cavity while an instrument is positioned through the trocar sheath.
It would therefore be desirable to provide improved surgical access devices and methods for their use in performing less invasive coronary artery bypass grafting and other thoracoscopic surgical procedures, and minimally invasive surgical procedures in general. It would be particularly desirable if such devices and techniques provided atraumatic retraction of soft tissue of the chest wall to create the largest possible surgical access window without resorting to a sternotomy or gross retraction or removal of the ribs. Preferably, such improved surgical access devices and methods would provide a flexible access lumen which could be positioned and sized to meet the individual patient""s physiology. The devices should have minimum height so as to extend as little as possible from the inner or outer surfaces of the chest wall. It would further be desirable if such access devices and methods allowed direct or magnified viewing of the internal procedure from outside the patient body, thereby decreasing the time and trauma associated with the internal surgical procedure, and increasing overall efficacy over both open surgical procedures and minimally invasive surgical procedures performed through the small trocar sheaths which have been relied on in the prior art.
2. Description of the Background Art
Conventional thoracoscopic techniques are described in Landreneau et al. (1992) Ann. Thorac. Surg. 54:800-807. Conventional open surgical procedures for performing coronary artery bypass grafting are described in Kirkland and Barratt Boyes, Cardiac Surgery, John Wiley and Sons, Inc., New York, 1993 (2nd Ed.).
A minimally invasive method for performing coronary artery bypass grafting using an anterior mediastinotomy, including excision of either the third or fourth costal cartilage, was described by Robinson et al. in J. Card. Surg. (1995) 10:529-536.
U.S. Pat. No. 5,391,156 describes a flexible endoscopic surgical port having a tubular body, the outer end of which is optionally divisible into a plurality of flaps, thereby matching the length of the tubular body with the thickness of a body wall. A retainer ring engages the flaps to hold the port axially, while the hoop strength of the tubular body holds the adjacent tissue in a retracted position. U.S. Pat. No. 4,274,398 describes a surgical retractor having elastic tubes which hold hooks under radial tension from a notched frame. U.S. Pat. Nos. 4,430,991, and 4,434,791, describe similar surgical retractor frames for use with hooked members. Such a system is commercially available under the trade name LoneStar Retractor System(trademark).
A surgical drape having a central open ring for insertion over known surgical retractors is commercially available from Becton Dickinson of Franklin Lakes, N.J. under the tradename Vidrape(copyright). Relevant minimally invasive methods and devices for heart surgery are described in U.S. Pat. No. 5,452,733; U.S. Pat. No. 5,571,215; U.S. Pat. No. 5,501,698; U.S. Pat. No. 5,588,949; and U.S. Pat. No. 5,799,661, the full disclosures of which are incorporated herein by reference.
In a first aspect, the present invention provides a retractor for providing surgical access to a body cavity of a patient through a passage in tissue. The retractor comprises an anchoring frame having an upper surface, a lower surface, and an opening therethrough which defines an axial axis. The anchoring frame is positionable through the passage into the body cavity. A flexible tensioning member is attached to the anchoring frame and extendable from the frame out of the body through the passage. The tensioning member is selectively tensionable to spread the tissue radially outwardly from the axial axis. Hence, it is the tension imposed on the flexible tensioning member which effects retraction of the tissue, rather than relying on the structural integrity of a tubular structure such as a trocar sheath.
Generally, an attachment mechanism on the tensioning member maintains tension so as to retract tissue from the passage. Hence, the tensioning member need only be capable of withstanding and transferring the tension imposed by the attachment mechanism, there being no need for a rigid structure having sufficient hoop strength to maintain the tissue in the retracted position. The resulting surgical access window need not be compromised by any rigid lumen wall or rigid blade-type structure, and the retraction load is distributed atraumatically over a wide area of the tissue by the flexible tensioning member.
Preferably, the anchoring frame will have a narrow profile configuration for insertion through an incision into the body cavity, and will be expandable to a wide profile configuration once inside the body cavity. The frame may comprise a variety of collapsible and expandable structures, including a ring of resilient material which expands to the large configuration when released. The tensioning member is preferably formed of a plurality of elongate tabs or strips of cloth, tape, cord, or strap material, ideally comprising an absorbent material such as gauze so as to absorb any fluids released by the tissue bordering the passage. Alternatively, an elastomeric or semi-elastomeric sheet or strip may be used.
In another aspect, the present invention provides a retractor for providing surgical access into a chest cavity defined by a plurality of ribs. The ribs are separated by intercostal tissue and an intercostal width. The retractor comprises an anchoring frame which is insertable into the chest cavity through a passage between two ribs, the frame having an opening. A flexible tensioning member extends from at least two opposing sides of the opening in the frame. The tensioning member is able to extend out of the chest cavity through the passage when the frame is within the chest cavity and the opening in the frame is generally aligned with the passage. The tensioning member may be tensioned to spread the intercostal tissue outward toward the two ribs. Such a retractor is particularly well suited for forming an anterior mediastinotomy or small thoracotomy for use in a less invasive coronary artery bypass grafting procedure or other cardiac procedure.
Generally, an attachment mechanism on the tensioning member maintains outward radial tension from outside the patient to hold the intercostal tissue in a retracted position. In some embodiments, the attachment mechanism comprises an adhesive disposed on the tensioning member to facilitate attachment to an outer surface of the patient""s chest. Optionally, a surgical film may be adhered to the exterior of the chest surrounding the passage to facilitate adherence of the tensioning member to the chest wall. In alternative embodiments, the attachment mechanism comprises a plurality of clasps or other coupling devices disposed about an outer ring structure which is positioned outside the body cavity.
In yet another aspect, the present invention provides an illuminated retractor for providing surgical access to a body cavity of a patient through a passage in tissue. The retractor comprises an internal anchor having an opening, the anchor being insertable through the passage and into the body cavity. A tissue restraining structure extends proximally from the internal anchor for holding the passage open sufficiently to provide direct visualization of the internal body cavity from outside the patient. Typically, an external anchor is spaced proximally from the internal anchor on the tissue restraining member. An illuminating device is disposed adjacent to the opening in the internal anchor to facilitate visualization of the cavity through the open passage.
In yet another aspect, the present invention provides a tissue retractor system for providing surgical access through an incision in tissue to a body cavity of a patient. The system generally comprises a retractor and a retractor delivery device. Specifically, the retractor comprises an anchoring frame having an opening, wherein the frame is restrainable into a narrow profile to facilitate insertion of the frame into the body cavity. The frame is expandable into a wide profile when inside the body cavity. A flexible tensioning member extends from the frame adjacent to the opening and is selectively tensionable to retract the tissue adjacent the incision, and is adapted to be secured in tension outside the body cavity.
The retractor delivery device comprises a device body having distal and proximal ends, and a pair of inward facing surfaces near the distal end which restrain a frame of the retractor therebetween to a small profile. A handle supports the inward facing surfaces from a proximal end. An actuator may be provided on the handle to effect expansion of the frame within the body cavity.
The present invention also provides a method for retracting tissue to temporarily widen a penetration into a body cavity, the method comprising positioning an anchoring frame against a tissue surface within the body cavity adjacent to the penetration so that an opening in the frame is aligned with the penetration. The frame has a width across the opening which is wider than the penetration. A tissue restraining member extending from the frame out of the body cavity through the penetration is tensioned so as to urge the tissue adjacent the penetration outwardly.
In a further aspect, the present invention provides a method for performing surgery on a patient""s heart, the heart being disposed within a chest cavity defined by a plurality of ribs, the ribs being separated by intercostal tissue and an intercostal width. The method comprises inserting an anchoring frame into the chest cavity through an incision between two ribs, wherein the frame has an opening and a width across the opening wider than the intercostal width. Tension is then imposed on a plurality of flexible tabs extending from the frame adjacent to the opening so as to widen the incision. Surgery is then performed on the heart using instruments positioned through the widened incision.